Field of the Invention
This invention relates generally to a thin film, flexible, wideband antenna configured on a dielectric substrate and, more particularly, to a thin film, flexible, wideband co-planar waveguide (CPW) antenna that may include transparent conductors so as to allow the antenna to be adhered to a visible part of vehicle glass, where the antenna is operable to receive right-hand circularly polarized signals for GPS/GNSS frequency bands or left-hand circularly polarized signals for satellite digital audio radio service (SDARS) frequency bands.
Discussion of the Related Art
Modern vehicles employ various and many types of antennas to receive and transmit signals for different communications systems, such as terrestrial radio (AM/FM), cellular telephone, satellite radio, dedicated short range communications (DSRC), GPS, etc. Further, cellular telephone is expanding into 4G long term evolution (LTE) that requires two antennas to provide multiple-input multiple-output (MIMO) signals. The antennas used for these systems are often mounted to a roof of the vehicle so as to provide maximum reception capability. Further, many of these antennas are often integrated into a common structure and housing mounted to the roof of the vehicle, such as a “shark-fin” roof mounted antenna module. As the number of antennas on a vehicle increase, the size of the structures required to house all of the antennas in an efficient manner and providing maximum reception capability also increases, which interferes with the design and styling of the vehicle. Because of this, automotive engineers and designers are looking for other suitable areas on the vehicle to place antennas that may not interfere with vehicle design and structure.
One of those areas is the vehicle glass, such as the vehicle windshield, which has benefits because glass typically makes a good dielectric substrate for an antenna. For example, it is known in the art to print AM and FM antennas on the glass of a vehicle where the printed antennas are fabricated within the glass as a single piece. However, these known antennas are generally limited in that they can only be placed in a vehicle windshield or other glass surface in areas where viewing through the glass is not necessary.
For those antennas that receive satellite signals, such as GPS, GNSS, SDARS, GLONASS, satellite radio, etc., the transmitted signals are left-hand or right-hand circularly polarized because the ionosphere acts to rotate the transmitted signal, which would otherwise affect linearly polarized signals. Thus, there is a need for a suitable antenna capable of being mounted on vehicle glass and being applicable to receive right-hand or left-hand circularly polarized signals.